报道了可饱和吸收体Cr4+:YAG的液相外延生长,对双掺杂Cr,Ca:YAG外延层的吸收特性进行了分析.通过对Cr离子掺杂浓度以及外延层厚度的控制,λ=1.064 μm的饱和与非饱和透过率差ΔT可以在5%～30%的范围内进行调节,满足单片式被动调Q微晶片激光器对饱和吸收体的设计要求.分析结果同时表明外延Cr,Ca:YAG层中还有Cr5+离子的存在.

The growth of saturable absorber Cr 4+∶YAG crystals by liquid phase epitaxy (LPE) is reported. The absorption characteristics of this co-doped Cr,Ca∶YAG epilayer is analyzed. The transmission variation ΔT (i.e. the difference between saturated and unsaturated transmissions at 1.06 μm) could be adjusted easily in a range of 5%～30% by adjusting the concentration of Cr and /or the thickness of the epilayer during LPE and or by polishing. It is believed that this Cr,Ca∶YAG epilayer is well qualified for the development of passively Q-switched monolithic microchip laser as a solid-state saturable absorber. It shows that there is also the existence of Cr5+ ion in this Cr,Ca:YAG epilayer.